Skulduggery amid the gently rolling vineyards of Tuscany has sent at least £10 million worth of one of Italy’s most celebrated red wines gurgling down the drain.

Saboteurs broke into the cellars of the Case Basse winery in the middle of the night, turned on the taps of the giant wooden casks in which the wine was maturing and allowed 60,000 litres of prized Brunello di Montalcino to pour onto the ground.

The huge lake of wine represented 80,000 bottles, each of which can sell for 170 euros or more – a total value of more than 13 million euros.

The nocturnal raiders did no other damage to the estate’s “cantina”, nor did they steal anything, deepening the mystery and suggesting that it was less a random episode of vandalism and more a deliberate act of spite.

The raid wiped out the last six vintages of the 6.5 hectare vineyard in the hills of southern Tuscany.

Gianfranco Soldera, who worked as an insurance broker in Milan before buying the estate in 1972, said he had no idea who might have been behind the raid on Monday night.

“We’ve never been involved in controversy and we’ve never received threats. We’ve suffered a serious blow, not just in economic terms, but we will not give up. The estate will survive, we have the strength and the courage not to quit.”

Case Basse is a small but highly acclaimed producer of Brunello di Montalcino, making around 15,000 bottles a year, which sell for up to 170 euros a bottle.

The wine has to be matured in barrels for at least four years before it can be sold under the Brunello di Montalcino name, so the vineyard will have nothing to sell until 2016 at the earliest.

The sabotage is being investigated by Carabinieri police from nearby Montalcino, a town popular with British summer tourists which is dominated by a 14th century fortress.

Fabrizio Bindocci, the president of the Brunello di Montalcino Consortium, said the sabotage would shock all 250 producers of the esteemed red in Tuscany.

Donatella Cinelli Colombini, the vice-president of the consortium, said: “I cannot think of a similar incident in this region in living memory. It is a dismaying affair.”